1. Field of the Invention
The invention relates generally to control systems for ink jet droplet apparatuses and more particularly to conditioning circuitry for improving signal to noise ratios of signals inputted to the control system.
2. Prior Art
Previously, signals carried over a line from a transducer for an ink jet droplet apparatus to a receiving control system to be acted thereon would arrive at the system with a relatively low signal to noise ratio making them at times only marginally useful as an indicator of what the transducer had actually sensed. This was due in part to noise encountered at the transducer source, but primarily noise was picked up along the line, particularly if the line environment was relatively noisy.
Attempts to solve this problem have generally taken three approaches. One could upgrade the quality of the transducer and/or line to preempt noise from being induced therein. Alternatively, the frequency selectivity of the receiving control system could be narrowed thereby allowing a lower signal to noise ratio to be used. A final possibility consisted of installing an interfacing circuit between the transducer-line and the receiving control system that would raise the signal to noise ratio thereby allowing even relatively noisy line signals, after being conditioned by the interfacing circuit, to be inputted to a control system having relatively wide frequency selectivity. The first and second approaches to the problem are relatively expensive and thus not entirely desirable.
A particular problem encountered in using the interface circuit approach mentioned supra has been how to generally separate the noise spectrum from the signal spectrum assuming they are mutually exclusive. Additionally and perhaps presenting the most difficulty, comprises the problem of how to reduce or eliminate noise relatively embedded in the signal spectrum when they are not mutually exclusive. Finally, a problem exists in obtaining digital-like signals from a relatively noisy analog-like transducer signal for interfacing with a downstream control system. The final supra mentioned problem being co-existent with the supra embedded noise problem in regards to the methodology of solving the pair of problems.